This invention relates to ergonomic eyewear that vertically redirects some portion of the wearer's visual field. Upward vision redirection improves ergonomics for several common sports including bicycling, motorcycle racing, swimming, and ski racing. Downward vision redirection improves the ergonomics of reading a book, working on a laptop or pad computer, or taking notes in a class.
Prior art for vision redirection falls primarily into three categories, sporting glasses for bicycling and swimming that direct vision upward, reading and computer glasses that direct vision downward, and ophthalmic prism correction systems for treating conditions such as diplopia.
Bicycle sunglasses and swimming goggles have long been identified as candidates for improvement by selective upward vision redirection. Many inventions have been proposed to address this perceived need.
U.S. Pat. No. 4,647,165 to Lewis discloses an optical system for bicycle riders. This system redirects vision using triangular prisms mounted to a frame. The frame pivots into the field of vision when the rider is looking down and pivots out of the way when the rider raises his head. These triangular prisms refract and reflect light.
U.S. Pat. No. 6,006,367 to Webster discloses swimming goggles divided into lower and upper panels and water sealed at their junction. The upper panel comprises a rectangular prism, the lower panel a transparent face plate. Light entering the prism's planar top surface is redirected to allow the swimmer to look forward while gazing through the upper panel. Light entering through the transparent lower panel is not vertically redirected.
Several inventions have been proposed that redirect vision and thereby improve the ergonomics of book reading or computer viewing.
U.S. Pat. No. 2,123,682 by Wingate discloses an optical appliance which enables the wearer to view objects situated at an angle to the direct line of vision. The device comprises an eyeglass frame having a pair of rectangular eye-frames, each of which carries a triangular prism constructed and situated in such a way that light entering the prism is refracted on entry, twice internally reflected, and refracted again on exit.
U.S. Pat. No. 4,077,703 by Pablo discloses an optical apparatus enabling a person wearing such apparatus to view objects at an angle to their direct line of vision while the person's gaze is fixed in a substantially direct line of vision. The apparatus is described as comprising prisms, removably attached to a frame which can be worn in front of the eyes or over a pair of reading and/or viewing glasses. These prisms comprise planar optical surfaces and utilize reflection to modify the light path.
U.S. Pat. No. 4,792,223 by Axelbaum describes an optical device worn over the eyes that utilizes a projecting planar reflector that re-reflects a lens reflection. The invention claims to allow simultaneous viewing of two images.
U.S. Pat. No. 5,173,720, Lee et al., discloses an eyewear field-of-view changer that includes an optical frame carrying a pair of highly reflective surfaces that permit a wearer to experience an angular offset between the direct line of vision and the effective line of vision.
U.S. Pat. No. 5,204,702 to Shapiro describes an apparatus and process for relieving eye strain from video display terminals. This system uses triangular prisms to redirect vision horizontally inward, in effect crossing the eyes, to reduce strain on the ocular muscles. These prisms refract light.
U.S. Pat. No. 6,280,031 to Zerkle discloses prismatic optical viewing glasses that afford the wearer a redirected field of vision while retaining peripheral viewing fields. This invention uses triangular prisms mounted on a visor. These prisms refract and reflect light.
U.S. Pat. No. 7,494,219 to Shahkarami discloses eyewear for redirected viewing with auxiliary lenses that provides a redirected view, including a visor configured to support a pair of triangular prisms. These prisms refract and reflect light.
Dolezal U.S. Pat. No. 5,042,910 describes a pair of glasses or goggles with a single prism secured in the field of view for vertically redirecting user's field of view.
The above prior art uses triangular prisms or mirrors to redirect the visual field. None of the devices appears to provide an ideal solution to the problem. Projecting mirrors and prisms add weight, increase wind resistance, are unbalanced and unwieldy.
Ophthalmic applications also use prisms to deviate light. Indeed, prism power is a standard component of eyeglass prescriptions. The prism power prescribes the amount of prismatic deviation (if any) needed to provide comfortable binocular vision.
Besides prisms and mirrors, a fresnel prism can also redirect light. A fresnel prism comprises an array of many small prisms and can be thinner and lighter than a conventional prism of the same power. Fresnel prisms are currently used to treat diplopia (double vision).
3M Corporation produces a product line called Press-On Optics that includes Press-On prisms used to treat diplopia. Press-On prisms are compression molded flat flexible PVC films embossed with a fresnel array of triangular prisms. A Press-On prism is trimmed to size using scissors, wetted with clean water, rotated to the correct orientation, then pressed to the rear surface of the diplopia patient's eyeglass lens where it adheres without other adhesive. Press-On prisms are convenient but deliver relatively poor visual acuity, compared even to other fresnel prisms.
High power prisms, including fresnel prisms, noticeably degrade visual acuity primarily due to chromatic aberration from dispersion. U.S. Pat. No. 6,934,084 by Pandya discloses an ophthalmic prism for diagnosing and correcting visual disorders comprising a transparent refractive prismatic component, a triangular prism or fresnel triangular prisms, combined with a blazed transmission diffraction grating. This composite prism is claimed to reduce chromatic aberration because refractive dispersion and diffractive dispersion operate in opposite directions and can be made to counteract. The prisms taught by this patent have planar optical surfaces with the angle of incidence of light being essentially normal to the lens surface.
What is needed is an unobtrusive, balanced, lightweight, non-projecting, optically optimized system capable of vertically redirecting light while maintaining good visual acuity. For some applications, such as bike riding, a practical system must allow the user to quickly switch back and forth between normal and redirected vision.
Accordingly, several advantages of one or more aspects of the invention are:
(a) to provide an ergonomic vertical redirection vision system in the form of eyeglasses or goggles that allow a user to look up or down, depending on the activity, while keeping the neck in a more neutral position than would otherwise be required;
(b) to provide an ergonomic vertical redirection vision system that maintains good visual acuity;
(c) to provide an ergonomic vertical redirection vision system that closely replicates the form factor of conventional glasses and goggles including such factors as size, weight, balance, and overall appearance;
(d) to provide an ergonomic vertical redirection vision system that adds no moving parts;
(e) to provide an ergonomic vertical redirection vision system that is practical to manufacture;
(f) to provide an ergonomic vertical redirection vision system that may be adapted for use with cycling sunglasses to allow a bicyclist to look forward while keeping the head down;
(g) to provide an ergonomic vertical redirection vision system for bicycling that allows the user to quickly and easily switch back and forth between normal and redirected vision;
(h) to provide an ergonomic vertical redirection vision system that preserves peripheral vision;
(i) to provide an ergonomic vertical redirection vision system that may be adapted for use with swim masks and swim goggles;
(j) to provide an ergonomic vertical redirection vision system that may be adapted for use with motorcycle eyewear to allow a rider or racer to look forward while keeping the head down;
(k) to provide an ergonomic vertical redirection vision system that may be adapted for use with skiing eyewear to allow a racer to look forward while keeping the head down;
(l) to provide an ergonomic vertical redirection vision system that may be adapted for use with plano or positive power reading glasses to allow a user to look downward for reading while keeping the head up;
(m) to provide an ergonomic vertical redirection vision system that may be adapted to allow a user to comfortably view a computer screen placed below optimum height while keeping the head up;
(n) to provide an ergonomic vertical redirection vision system that may be adapted to allow a computer user to easily switch views between a computer screen and a keyboard while keeping the head up;
(o) to provide an ergonomic vertical redirection vision system that may be adapted for use in bifocals;
(p) to provide an ergonomic vertical redirection vision system that may be used by students to simultaneously watch a lecture and take notes without moving the head;
(q) to provide an ergonomic vertical redirection vision system that is practical and inexpensive to manufacture; and
(r) to provide an vertical redirection vision system that is easy to clean and practical to maintain.